Process for the manufacture of crimped filament yarns



3, 1963 F. SCHMIEDER ETAL 3,112,551

PROCESS FOR THE MANUFACTURE OF CRIMPED FILAMENT YARNS Filed Dec. 22,1959 INVENTORS MPM? W ATTORNEYS United States Patent 3,112,551 PRBCESSFOR THE MANUFACTURE 6F CPED FILAMENT YARNS Felix Schmieder, Frankfurt amMain, Joachim Hildebrandt, Hattersheim (Main), and Walter Kromhach,Neuenhaiu, Taunus, Germany, assignors to Farbwerke HoechstAlttiengesellschsit vormals Meister Lucius t Briining, Frankfurt amMain, Germany, a corporation of Germany Filed Dec. 22, 1959, Ser. No.861,357 Claims priority, application Germany Dec. 31, 1958 Claims. (Ci.28- -72.)

The object of the present invention is a process for the manufacture ofpotentially crimped filament yarns of synthetic linear high polymerssuch as, for example, polyethylene terephthalate, poly-e-caprolactam,polyhexamethylene-diamine adipate. By the term potentially crimped thereis to be understood in this connection that multifilament yarns treatedaccording to the invention are capable of crimping when allowed toshrink.

It has already been described that crimped filament yarns of linearpolymers are obtained by heating a stretched filament yarn to atemperature of 30 to C. below the melting point, stretching the filamentyarn beyond its yield point, cooling the filament yarn and deviating itat a sharp edge in such a manner that the threadine of the filament yarnforms an acute angle at the deviating edge, and then allowing thefilament yarn to shrink. This process is carried out with the stretchedfilament yarn and constitutes, therefore, an aftertreatment .or afinishing operation.

Now we have found that potentially crimped filament yarns of linear highpolymers, the crimping of which only appears after they have beensubjected to a shrinking treatment, are obtained when the filamentyarns, in the course of the continuous stretching to two to eight timestheir original length, are heated on one side for a short period bypassing the filament yarn-s at a speed of more than 100 m./minute,preferably more than 300 m./minme, over a small surface heated at atemperature within the range of 300 to 900 C., preferably 500 to 600 C.,while deviating the filament yarn in a manner such that the section ofthe filament yarn before the heated surface forms an angle of 130 to 170with the section of the filament yarn after the heated surface. Thefilament yarn touches the small, highly heated surface over a distanceof at least 0.3 mm. and at most 5 mm. The heated surface can, forexample, be an electrically heated resistance wire having a diameter of,for example, 2 mm. When the filament yarn passes over such a surface atthe high speed of, for example, 400 rn./minute, the time of contact isvery short, and it has proved to be useful when said time of contact iswithin the range of 0.00008 to 0.01 second. When observing theseconditions, the yarn is not heated thoroughly but only on one side dueto the fact that its filaments are only heated on that side on whichthey have touched the heated surface for a short period of time.

When stretching the filament yarns of synthetic linear high polymers,there is often arranged Within the zone of stretching, i.e. between thefeed roller and the drawing roller, 3. snubbing pin or a snub'bingroller, which may be heated or not heated, with the purpose oflocalizing the stretch point in the filament yam during the stretchingprocess. The small, highly heated surface which the filament yam touchesWhhe being deviated, shall then, according to the invention, be arrangedbetween the snu bing device and the drawing roller.

In this process it has in many cases proved to be advantageous tomoisten the filament yarn with water prior to being brought into contactwith the heated small surface, possibly with the addition of a wettingagent. When proceeding in this manner, it is necessary to heat the wireto a higher temperature in order to attain the desired effect. In orderto avoid that the heated surface is worn out by the filament yarnpassing over it, it is expedient to cause the filament yarn slowly tomove to and fro in a cross-direction to its threadline.

The process of the invention constitutes a considerable advance in theart inasmuch as it can be applied with little expenditure to thestretching machines customarily used for the manufacture of filamentyarns which are mers exhibiting a good crimp effect in a simple and,

above all, economic manner. After having undergone the treatmentaccording to the invention, the filament yarns first have a smoothappearance. Crimping only appears when the filament yarns are shrunk,for example, by heating them by air from 100 to 240 C., by water from toC., but also when brought into contact with a plate or roller having atemperature ranging from 100 to 240 C.

However, there can also be fabricated woven or knitted goods fromthe-still smooth filament yarns treated according to the invention, saidwoven or knitted goods being allowed to shrink by subjecting them to atreatment with hot air, hot Water, as mentioned above, or with asuitable solvent such as, for example, ethylene chloride or acetone, inthe course of which treatment the filament yarns shrink and crimp thusimparting to the woven or knitted fabric a high degree of elasticity.

The FIGURE illustrates a form of apparatus for carrying out the processof the invention.

The following examples serve to illustrate the invention, but they arenot intended to limit it thereto:

Example 1 A meltspun undrawn multifilarnent yarn 1 consisting of 25single filaments of polyethylene terephthalate was taken off thespinning bobbin by a feed roller 2 and a separating roller 3 at a speedof m./minute. In order to localize the stretch point, the yarn l Waspassed once around a stationary snubbing rod 4 heated at 90 C. andhaving a diameter of 60 mm. The yarn was heated on one side by passingit over a resistance wire 5 electrically heated at 500 C. and having adiameter of 2 mm, While simultaneously deviating the yarn from thestraight threadline in a manner such that the two sections of yarnbefore and after the hot Wire formed an obtuse angle of The yarn wasdrawn off by drawing roller 6 with separating roller 7 at a speed of 400m./minute and the yarn, which had acquired a potential crimping, Waswound on a bobbin. When the yarn was allowed to shrink in the free statein boiling water, the yarn crimped and contracted to 40% of its originallength.

Example 2 A spun yarn of polyethylene terephthalate of 660 deniershaving 50 individual filaments was taken off the spinning bobbin by anunheated feed roller, around which the yarn was passed in several wraps,and conducted, also in several wraps, over a s-nubbing roller heated at105 C. The yarn was then passed over a roller, installed in a water bathand driven by the friction of the yarn, and subsequently at an angle of155 over a metal wire heated at about 840 C. to the drawing rollerdriven at a speed 4.4 times higher than that of the feed roller. In thecourse of this operation, the yarn was stretched down to deniers. Whenthe yarn was then- Patented Dec. 3, 1963 A meltspun yarn ofpoly-e-caprolactam of 180 deniers having 9 individual filaments wastaken off the spinning bobbin by an unheated roller around which theyarn was passed in several wraps, and was stretched between an unheatedsnubbing pin, around which the yarn Was passed at an angle of about 180,and a dnawing roller driven at a peripheral speed being four times ashigh as that of the feed roller at a draw-cit speed of 400- rnJrninuteinto a yarn of 45 deniers. The yarn is then passed at an angle of 140over a Wire installed before the drawing roller and heated at 570 C. Theyarn was then wound on a bobbin and processed into warp-knitted goodswhich were allowed to shrink in the relaxed condition at 180 C. Due tothe yarn getting crimped, the goods had an especially soft and fullhandle.

We claim:

1. A continuous process for making intently crimped filament yarn ofsynthetic, thermoplastic, linear high polymers, said yarns beingadaptable to crimping by subsequent shrinking, which process comprisesdrawing unstretched filament yarn by stretching said yarn to two toeight times its original length While heating one side thereof for0.00003 to 0.01 second by passing said yarn at a speed of more than 100meters/minute over a small surface heated at a temperature between 300C. and

. 900 C., the yarn touching said heated surface only over a distance of0 .3 millimeter to 5 millimeters and being changed in direction at theheated surface such that the yarn approaching the heated surface formsan obtuse angle of between and with the yarn leaving the heated surface.

2. A process as claimed in claim 1, in which the sur- 'face is heated ata temperature within the range of 500 to 600 C.

3. A process as claimed in claim 1, in which an electrically heated wireis used as heated surface.

4. A process as claimed in claim 1, in which the filament yarns, priorto passing over the heated surface, are moistened with water.

5. A process as claimed in claim 1, in which the filamerit yarns, priorto passing over the heated surface, are moistened with the aqueoussolution of a wetting agent.

References Cited in the file of this patent UNITED STATES PATENTS2,919,534 Bolinger et al Ian. 5, 1960 2,974,391 Speakman et a1. Mar. 14,1961 3,024,517 Bromley et al Mar. 13, 1962 FOREIGN PATENTS 164,127Australia July 15, 1955 564,382 Canada Oct. 7, 1958 558,297 GreatBritain Dec. 30, 1943 780,755 Great Britain Aug. 7, 1957

1. A CONTINUOUS PROCESS FOR MAKING LATERNTLY CRIMPED FILAMENT YARN OFSYNTHETIC, THERMOPLASTIC, LINEAR HIGH POLYMERS, SAID YARNS BEINGADAPTABLE TO CRIMPING BY SUBSEQUENT SHRINKING, WHICH PROCESS COMPRISESDRAWING UNSTRETCHED FILAMENT YARN BY STRETCHING SAID YARN TO TWO TOEIGHT TIMES ITS ORIGINAL LENGTH WHILE HEATING ONE SIDE THEREOF FOR0.00008 TO 0.01 SECOND BY PASSING SAID YARN AT A SPEED OF MORE THAN 100METERS/MINUTE OVER A SMALL SURFACE HEATED AT A TEMPERATURE BETWEEN300*C. AND 900*C. THE YARN TOUCHING SAID HEATED SURFACE ONLY OVER ADISTANCE OF 0.3 MILLIMETER TO 5 MILLIMETERS AND BEING CHANGED INDIRECTION AT THE HEATED SURFACE SUCH THAT THE YARN APPROACHING THEHEATED SURFACE FORMS AN OBTUSE ANGLE OF BETWEEN 130* AND 170* WITH THEYARN LEAVING THE HEATED SURFACE.